Subsurface imaging is widely used in many fields, such as archeology, forensic sciences, geotechnical and environmental engineering, and construction. Subsurface imaging is conducted using any number of known imaging technologies. One such technology is ground penetrating radar (GPR).
When GPR is used, the imaging is accomplished by positioning and moving a sensor, such as a GPR transmitter/receiver antenna assembly, on a path over a target surface. The target surface may be ground or road surface, or the wall or ceiling of a tunnel, cave, or the like. In order to obtain accurate data, it is desirable to maintain the sensor at a fixed operational distance from the target surface. This operational distance is usually quite close (e.g. within several centimeters) to the target surface. Accordingly, it is also desirable to protect the sensor from colliding with obstacles, debris, or other irregularities on the target surface.
One known solution for the above problems is a four-wheeled cart which is pushed by the operator along the target surface. The sensor is suspended from the cart behind the front wheels at the operational distance from the ground. The sensor is suspended from the cart by four pivoting struts located at each corner of the sensor. The struts are free to pivot about their connection points to the cart. The struts permit the sensor to swing out of the way when the sensor impacts an obstacle or when the grade of the target surface changes.
However, the cart described above is not suitable for all subsurface imaging applications. For example, the cart is not suitable for applications which require the sensor to travel long distances or at high speeds, such as when the sensor is towed behind motorized vehicles.
Accordingly, there is a need for an improved apparatus for transporting a sensor, which is suitable for travel over long distances or at high speeds.